SELECT
 E1.EMP_CODE AS CODE
 ,E1.EMP_LAST_NAME AS SURNAME
 ,E1.EMP_FIRST_NAME AS NAME
 FROM
  (SELECT * FROM EMP WHERE VALID_FLG = '1') AS E1
  LEFT OUTER JOIN EMP AS E2 
        ON TRIM(E1.EMP_LAST_NAME) = TRIM(E2.EMP_LAST_NAME)
        AND TRIM(E1.EMP_FIRST_NAME) = TRIM(E2.EMP_FIRST_NAME)
;